Block copolymers of polycarbonates including segments of other polymers have been known, see for example, Goldberg, U.S. Pat. No. 3,030,335, Adelmann, et al., U.S. Pat. No. 4,252,922, and Behnke et al., U.S. Pat. No. 4,436,839 who disclose block copolymers of bisphenol-A carbonates including segments derived from polyalkylene glycols. In Schreckenberg et al., U.S. Pat. No. 4,217,437, the polyalkylene glycols are advantageously end-functionalized, e.g., with diphenol carbonates. Such block copolymers are useful per se as film formers and shaped articles because of toughness conferred on the polycarbonates by the segments of other polymers. The block copolymers can also be blended with polycarbonate resins, and a whole host of other thermoplastic addition and condensation polymers to provide thermoplastic addition and condensation polymers to provide thermoplastic molding compositions showing markedly improved resilience properties compared with the unblended resins.
It is also known that a highly useful family of heat resistant thermoplastic polymers is comprised of polyetherimide resins made by reacting a bis ether anhydride and an aromatic diamine. See, for example, Heath and Wirth, U.S. Pat. No. 3,847,867, who discloses the reaction product of 2,2-bis[4-2,3-dicarboxyphenoxy phenyl] propane dianhydride (BPA-DA) and metaphenylene diamine. The linear polymer is terminated with amino groups, and has a very high molecular weight and high melting point (Tg, typically=216.degree. C.). Such a material cannot be readily blended with aromatic polycarbonate, because mixtures with two Tg's are obtained, one for the polyetherimide resin, and one for the polycarbonate. Furthermore, because of the amino terminal groups, polyetherimides cannot be successfully used as blocks in copolymers with aromatic polycarbonate segments, as is done with polyethers. Moreover, no method is known in the art to functionalize high molecular weight polyetherimide resins to accommodate their introduction as blocks into resin copolymers and, even if there were such methods, the length of the segments would probably be too high to provide a composition that would thermoform readily in conventional equipment.
It has now been found that an entirely new approach will solve the above-mentioned problems, and this is the subject matter of the present invention. The copending application of Edward Norman Peters, Ser. No. 784,362, discloses a method for preparing polyetherimides which are end functionalized with hydroxyl groups. When such polyetherimides are reacted with a polyhydric phenol and a carbonate precursor, there is surprisingly obtained a block copolymer which exhibits only one glass transition temperature Tg. Such copolymers also exhibit a high intrinsic viscosity, making them useful as engineering thermoplastics, and they are surprisingly compatible with other resins making available a number of new molding compositions.